(CNN)Ken Howard, who starred in the 1970s series "The White Shadow," had notable guest roles in such programs as "30 Rock" and was the head of the SAG-AFTRA actors' union, died Wednesday. He was 71.

Howard's death was confirmed by a statement from SAG-AFTRA (http://www.sagaftra.org/sag-aftra-statement-passing-sag-aftra-president-ken-howard#sthash.2d0fvu7W.dpuf).

"We are deeply saddened to announce that SAG-AFTRA President Ken Howard passed away today," the union said. "Ken was an accomplished actor, author, teacher and unionist whose steady leadership as president
of Screen Actors Guild positioned him to guide the union's historic 2012 merger with American Federation of Television and Radio Artists. In addition to his many professional credits, awards and other laudatory work,
he led the union for nearly seven years and was devoted to the interests of its membership."

The cause of death was not announced.

The Yale-educated Howard first rose to fame for his portrayal of Thomas Jefferson in the 1969 musical "1776," a role he also performed in the 1972 screen version. In 1970, he won a Tony for his performance in the work "Child's Play."

But for many fans, he was known for starring as Ken Reeves, the white basketball coach of an inner-city Los Angeles high school in the series "The White Shadow." The 6-foot-6 Howard, a high school star in his own right, had been
the only white player on his team and pitched the idea to producer-writer Bruce Paltrow.

"The White Shadow" never scored highly in the ratings but was lauded for its unflinching storylines -- in one episode a player was shot to death during a robbery -- and terrific performances. Such actors as Kevin Hooks and
Timothy Van Patten first made their names on the CBS drama, which ran from 1978 to 1981.

After "The White Shadow" left the air, Howard appeared in a number of TV series and movies. He was a regular on "Dynasty" and "The Colbys" in the mid-1980s, popped up repeatedly on "Murder, She Wrote" and was the head of Kabletown in "30 Rock."

He also appeared in such movies as 1994's "Clear and Present Danger," 1999's "At First Sight" and 2007's "Michael Clayton."

He won an Emmy for his performance in the TV movie "Grey Gardens."

In 2009 he became head of the Screen Actors Guild. That union merged with the American Federation of Television and Radio in 2012.

SAG-AFTRA praised Howard's leadership in its statement.
"He will be remembered not only as the final president of Screen Actors Guild and the man who led it successfully to unite with AFTRA, but also as the first president to be elected by the members of SAG-AFTRA," the union said.
"He was proud and honored to embody that continuity."

According to the union, Howard is survived by his wife, Linda Fetters Howard, and three stepchildren from a previous marriage.

Howard was previously married to Margo Howard, the daughter of Ann Landers and a former advice columnist herself. She said in a tweet, "My favorite ex-husband has died. He was a lovely guy. RIP Ken Howard."